1. Field of the Invention
This invention relates to a welding machine, and more particularly to a welding device in which a welding assembly mounted on a wheeled platform may be positioned in either of two selectable welding positions, a wire core is supplied and smoothly guided, and the overall operation is stable.
2. Description of the Prior Art
The one-machine, one-welding position concept was customary in the art of auto welding machines except where a welding object required all-position welding on a continuous basis. In recent years there have been developed auto welding machines movable into two welding positions and capable of achieving both horizontal fillet welding and flat position welding with the same configuration. There are two types of position converters for welding machines: the provision of an attachment for conversion from a primary welding position to a second welding position and the provision of a rotary shaft at an intermediate point between two changeable welding positions for rotation of a wire supply device. The former, however is disadvantageous in that conversion is laborous and requires special fittings. While the latter is advantageous as to manipulability over the former, it is necessary to change the fittings for the wire supply device when it is desired to alter the angle of a torch nozzle since the wire supply device is mounted integrally with the torch nozzle. In other words, a welding wire from the wire supply device must be guided to the torch nozzle in a rectilinear fashion so that the torch nozzle and the wire supply device are held integrally and in a linear positional relationship. To this end, for auto welding machines with wheeled platforms but limited space, there is the need to change the fittings for the wire supply devices at the time of altering the welding position. It is therefore desirable to exploit welding machines which are easily alterable in welding position without changing the fittings for the wire supply devices.
In most conventional devices, either the left or right side of the wheeled platform is located along the weld line. Whereas the wire supply device is positioned above the wheeled platform in a horizontal fillet welding position, upon changing to a flat welding position, the torch nozzle is positioned right above the weld line and the wire supply device integral with the nozzle extends from the platform into the weld line side so that the equilibrium thereof is lost. To maintain balance, the wheeled platform must be provided with a weight so as to be heavier than otherwise necessary. This results in inconveniences when manipulating and driving the machine. It is desirable that auto welding machines be as light in weight as possible to gain manipulability. The supply wire (full load) occupies the largest percent of the overall weight of the machine and the wire supply device occupies the second largest. While the center of gravity of the overall machine is determined mainly by those two components, there is the requirement that the center of gravity be unvariable to ensure stable traveling movements of the platform regardless of whether the torch nozzle changes in position.
As discussed previously, auto welding machines are adapted such that the weld line is located on either the left side or the right side of the wheeled platform. The prior art auto welding machines are either so-called left handed devices or right handed devices which are available on only one side of the weld line with the traveling direction being changed for the other side. There is a requirement for a new automated welding machine that is available on both sides of the weld lines despite a fixed traveling direction.